IMO J-20's EOPDS aperture mounted at the front on the top of the nose likely is for dorsal+forward angles, given its very similar position and size to the EODAS aperture to F-35.
J-20 5th Gen Fighter Thread VI
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IMO J-20's EOPDS aperture mounted at the front on the top of the nose likely is for dorsal+forward angles, given its very similar position and size to the EODAS aperture to F-35.
I would argue, given how the top window on the J-20’s is angled and shaped in comparison to the F-35’s, that there is probably a greater emphasis on the dorsal aspect for the J-20’s than the F-35’s. Either way, I think the main point is that the arpeture on top of the nose for both is not the primary forward looking IR sensor.
Yes I think the top/nose aperture for J-20 clearly isn't the primary forward looking IR/EO sensor.
That goes to the chin mounted EOIRST.
However I think the top/nose aperture for J-20 does have forward looking roles, for example I expect it to fulfill a FLIR/EVS role in future if it doesn't already have it.
Agreed on complementary forward looking roles for the top nose sensor but the point is the forward looking area of the arpeture is far too small and limited to be a primary forward looking sensor.
@TerraN_EmpirE:
Would an optical/ir sensor ever match a radar vs a stealth aircraft suppressed in the radar bands? Moreover, you have scaling issues. The current size of the largest hobbyist camera sensor is roughly .0027 m^2. The size of a F-22 AESA is roughly .67 m^2. That's a 248 times difference. If, say, the AESA radar on a J-20 is replaced with a large optical sensor, complete with large lens, you could possibly exceed the range of a modern radar, especially considering that X-band radars are horizon limited.
Funny thing is, we could be back to the days of the Red Baron, where he used the sun as optical camouflage. Correspondingly, we could see pilots use the sun or the moon for similar purposes, or use stars to block IR readings.
Would an optical/ir sensor ever match a radar vs a stealth aircraft suppressed in the radar bands? Moreover, you have scaling issues. The current size of the largest hobbyist camera sensor is roughly .0027 m^2. The size of a F-22 AESA is roughly .67 m^2. That's a 248 times difference. If, say, the AESA radar on a J-20 is replaced with a large optical sensor, complete with large lens, you could possibly exceed the range of a modern radar, especially considering that X-band radars are horizon limited.
Funny thing is, we could be back to the days of the Red Baron, where he used the sun as optical camouflage. Correspondingly, we could see pilots use the sun or the moon for similar purposes, or use stars to block IR readings.
Why u compare hobby sensor with military sensor? U can make visible/IR sensors as big as u want, it's just a money problem.
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You can make much larger optical sensors.
Just think about it. You can make a camera using CMOS processes. There are 300mm diameter wafers. You can even make arrays of them.
A typical problem with IR sensors though is that they need to be cooled down to operate with high sensitivity.
That's overkill. You can use a photodiode array if you're not space constrained and don't care about resolution that much. Also it's pointless to cooldown IR sensors in that sort of environment because your background noise is higher than your thermal noise.
Atmospheric lensing also makes optical imaging at long distances impossible.
Problem with IR / optical sensors is that it's a lens / sensor combo. A f/1.4 lens for Full Frame is not going to be the same size as a f/1.4 lens on Medium Format. In fact, an f/1.4 lens would be equivalent to f/0.8 or something like that, meaning the lens would be way larger to take full advantage of the sensor. In fact, the main limitation will be lens size, until resolution becomes aperture limited and you need to go up to a larger sensor. The other advantage of a larger sensor would be DIRCM resistance; part of the sensor could be burnt out by lasers, but the other part would remain usable, and the larger the sensor, the harder it becomes to burn completely.
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